Ruler



c. H. LITTLE Sept. 17, 1929.

RULER Filed DSG. 18y 1920 IIWIELI@ ,W is@ Patented Sept. 17, 19.29

UNITED STATES PATENT OFFICE CHARLES E. LITTLE, OF EAST CLEVELAND, OHIO RULER Application flied December 1.8, 1920.

This invention relates to rulers, such as scales, and straight edges, and is an improvement over the constructions disclosed in my prior patents, Nos. 1,274,291 and 1,274,292, granted July 30, 1918.

In my prior patents I have shown rulers having features of construction designed to impart to the rulers the chief advantages of both Wooden and metal rulers, heretofore commonly employed, and at the same time to eliminate certain Well-known disadvantages of both types. l

In both my prior patents a nonqvarping ruler body or core Was utilized, this being accurately formed, preferably from sheet metal, so that it Would be light in Weight, and the design was such that it would be suliiciently stiflz and rigid for ordinary purposes. To these met-al bodies Celluloid or pyroXylin coverings were applied either in the form of strips, as disclosed in Patent No. 1.274,291, or in the form of a coating, as disclosed in Patent No. 1,274,292, Which coating I proposed to apply from pyroxylin in a substantially liquid state in some suitable Way as by a dipping or spraying process.

While the construct-ionsI disclosed in my prior patents answer the major portion of the requirements, I have by the present invention effected certain important improvements which pertain both to the covering of the core or ruler body which is adaptable for both scales and straight edges, and also to the core itself.

This covering While preferably entirely encasing or enclosing the ruler body, and in that Arespect being similar' to the coating or covering of the ruler body ot my prior Patent No. 1,274,292, is in accordance with the present invention applied a covering,

vpreferably Wholly or partially previously formed, and While the covering of the present improved ruler has the desirable characteristics of the covering or coating of my patent just referred to, it has certain marked additional advantages which Will be referred to in the following description.

marized as consisting in certain novel fea- Serial No. 431,537.

tures and characteristics Which will be described in the specication and set forth in the ap Jended claims'.

In t e accompanying sheet of drawings wherein I have shown certain forms or em bodiments of my invention, Fig. 1 is a top plan view With parts broken away, of a scale embodying the principal features of the invention; Fig. 2 is a fragmentary longitudinal sectional view of the same; Fig. 3 is a transverse sectional View; F ig, 4 is a fragmentary bottom views; Figs. 5 and 6 are transverse sectional views respectively through the covering and through the metal core or ruler body as they are preferably formed; Fig. 7 is a perspective View of a portion of the scale showing the manner in which the covering is slipped over the core or ruler body; F 8 is an enlarged partial transverse sectional View of the Celluloid coverings; Figs. 9, 10 and 11 are transverse sectional views through a straight edge formed in accordance with the invention, these three views showing different embodiments of the invention.

Referring now to the drawings, and lirst to Figs. 1 to 8, which show my invention applied to a ruler adapted to be provided With graduations, and commonly called a scale, this ruler or scale includes a core or body 10 which is non-warping and permanent in the sense that it will retain its shape under ordinary usage, and which has the right degree of stiffness and rigidity. For this purpose I prefer to use a light metal, such as aluminum or a magnesium aluminum alloy Which is lighter, stiffer and stronger than aluminum. By the use of `a metal of this kind, Which is suliiciently light in Weight, and has the other necessary requirements, the core can be made solid as herein illustrated. A. core of this type can be formed in various Ways, such as by a rolling, eX- truding or drawing process which will produce Without machining, a strip or body uniform in cross section at all points of its length, and having straight parallel edges. The extruded or drawn core is peculiarly fitted for this purpose in vieiv of the fact that in the process of forming it, it receives a skin or surface hardening which adds to the stiffness of the core, and is free from bending or internal stresses due to ma- Chining.

As shown most clearly in Fig. 6, the Core 10 has upper and lower faces 10Q and 10" which are preferably i'lat and parallel, and beveled marginal portions 10C which incline downward from the upper face 10, substantially but not quite to the lower face 10b, leaving narrow flat edges of approximately one-sixty-fourth of an inch (more or less) in width. Likewise, the core when it has been Cut to the right length for the scale, is provided with tapped openings 10d to accommodate screws l1 for securing to the scale chuck plates, one of which is shown at 12 in Fig. 1; these Chuck plates when employed, adapting the scale for use with a drafting machine, although it is immaterial Whether these openings 10d are provided in the Core or body 10, before after the en- Closing Covering is applied to the core. This connection to solid metal gives a substantial hold at the end of the ruler which practically does away with any slight motion at this point, this being especially desirable in long rulers or-.straight edges. It is to be understood also, that the Chuck plates, and hence the openings 10 will be omitted in the event that the scale is to be used as a separate tool, and not in a drafting machine.

After the core or body 1.0 is formed into the right length, it is encased in a covering 13, which preferably entirely encloses the core, and which is preferably formed of celluloid or some other suitable nitroderivative of cellulose, such as pyroxylin or other suitable substance having certain Well-known properties or cha "acteris 4cs of Celluloid, i. e. which in its finished st is hard, smooth, easily movable over drafting paper, and Will not soil the paper; which is tough in the sense that it will .not chip olf, and can be flexed without liability of breakage or tearing; which has cohesive properties such that line smooth lines and characters can be Cut therein; which undergoes a shrinkage that will Cause the covering to tightly grip the core or body and retain permanently its shape and accuracy; and which for use in producing the straight edges can be made in transparent form, to form the covering and also transparent edges Which are very desirable for straight edges. Inasmuch as Celluloid has all these properties and Characteristics, and others which admirably adapt it for this use, Celluloid is the preferred material for this covering. The word Celluloid is used in the claims as applicable to any material having the above characteristics, or the major portion of them.

The Covering 13, can perhaps be made to advantage in dil'l'erent ways, but preferably it is extruded in the form of a tube of the same shape, especially in its interior dimensions as the shape of the core or body 10 and of substantially its size, though as will subsequently appear, the external dimensions of the tube need not, and preferably do not coincide piecisely with the external dimensions of the core or body 10.

At any rate, when the tube or covering and the core or ruler body are formed in proper lengths for a scale of given length, the tube is slipped over the core, the interior dimensions of the tube being such that when this is done, the tube or covering will fit tightly onto the Core, and everywhere conform to its shape.

Generally at this point in the manufacture of the ruler, the Celluloid covering is allowed to seasonl- By way of explanation of this term, it may be stated that as well known, Celluloid undergoes a Constant shrinkage; but the shrinkage is Comparatively rapid for a period immediately after the Celluloid formed, due to the rapid initial evaporatien of the solvents used in forming the Celluloid. This shrinkage, which is the seasoning referred to above, is of Considerable importance in the formation of the present improved rulers inasmuch as it Causes a very decided or intense gripping or adherence of the sheath or covering to the core, and this is an important factor in the attainment of the high degree of accuracy and permanency which my improved rulers possess.

The covering then Completed by the Closure of the ends of the tube, preferably by inserting in the ends of the tube up against the ends of he core 10, filler pieces 14, rounded at the bottom as shown in Fig. 2, these filler pieces being formed of wood or other material to which Celluloid can be effectively cemented, and by cementing the ends of the tubes to these filler pieces and also Cementing together the top and bottom walls of the tube. In Fig. 2 the bottom wall of the tube is shown as brought up around the rounded portion of the filler piece 1/1, and the top wall is brought down and lapped over it as shown'at 15. In this manner a very effective seal is obtained which will hold against the shrinkage of the Celluloid. I do not regard it essential that these filler pieces 14 be employed, as they may be omitted, especially in so ne instances as when the Core has a con'iparatively low temperature Coefficient, in which event the end portions of the tube Can be cemented together to form the end closure and seal, or if desired, other Ways of sealing the ends of the tube may be employed.

t is generally the case that the Celluloid Covering is allowed to shrink or season before'the end of the'. tube is closed, as above explained, but in some instances it may be desirable to close and seal the ends of the tube before this seasoning takes place, in which event the ruler will be subjected to longitudinal shrinkage stresses of the celluloid., whereas by sealing the ends of the tube after the initial shrinkage or seasoning, the stresses are chiefly of a transverse nature Then to complete the scale its marginal portions are provided with the cut graduations and characters indicated at 16, these graduations being brought down to the Iedges of the covering, which edges are square, as will be seen by reference particu larly to 8., as is highly desirable for accurate drafting work.

It might be mentioned at this point that the square edges of the core and of the covering itself are novel important characteristics of the present scale not possessed at least to a sufficiently high degree by the rulers shown in my prior patents, and it should be noted also, that the entire .flat ruling edge is formed of Celluloid, which is not the case with prior rulers having Celluloid strips attached to their marginal portions.

Additionally my present ruler with the covering previously formed and applied by the method above explained7 while possessing all the advantages of the coating or covering applied uniformily with the pyroxylin or celluloidal substance in a liquid form, as explained in my Patent No. 1,272,292, has important advantages over the coating or covering applied by my former method. In both instances the coverings completely enclose the cores or ruler bodies, and in both instances the non-warping cores hold the coverings in their initial accurate shape, and in both instances the coverings strongly adhere to the cores, though in the present instance the character of the adherence between the covering and the core is of a somewhat different mechanical character than in my prior ruler. In the way of additional advantages, however, I might mention that with the covering applied in accordance with the present invention, i. e., previously formed and slipped over the core, not only can a somewhat smoother and thicker covering be obtained, but the coveringof the ruler made in accordance with the present invention is more durable and less liable to chip off than the coating or covering of my prior ruler. But a more important advantage lies in the fact that as already intimated, the exterior shape of the covering or sheath need not coincide with the interior shape, That is to say, instead et the covering being uniform in thickness at all points, I may make certain parts thicker than others. For example, the beveled portions 13a may be, and preferably are thicker than the parallel top and bottom portions of the covering, and I am enabled by the present method to provide relatively thick or heavy edge portions 13, as clearly shown in F ig. 8. This last mentioned feature leaves ample material for planing the Celluloid edges to exact straight and parallel lines, either in manufacture, or when the edges have been marred by rough usage. My improved rulers, as hereinl made, can be produced inexpensively, this latter being` an advantage over even the ordinary wooden rulers, especially in view of the fact that the loss in producing the latter is excessive, due to the wastage caused by warping. Finally it might be mentioned that inasmuch as the adherence between the core and covering is of a mechanical nature, it is possible to make the ruler so as to allow for a very slight longitudinal relative movement between the core and covering to compensate for the differences in their temperature coefficients which may be desirable in comparatively long rulers.

While a Celluloid covering` in the form of a seamless extruded tube is now regarded as preferable, I do not wish to be confined to a tube which is seamless, and in the event a seamed tubular covering is employed, I do not wish the invention in its method aspect to be limited to one whose seam is closed prior to the insertion of the core in the sheath.

Though the invention has great utility in the production of rulers of the scale type, it is equally advantageous in the manufacture of rulers of the straight edge type, which are formed in the same manner, and will have the chief structural characteristics of the scales made by this invention, modification being made only in the cross sectional shape of the core and covering. Under the circumstances, simply cross sectional views such as 9, 10 and l1 are thought to be suflicient to illustrate this adaptation of the invention.

The straight edge has a core or body 1.7 which may be formed by any of the methods mentioned for the production of the cere 10, or otherwise if desirable, but in this instance the core is rectangular in cross section. The core is completely enclosed by a covering` i8, consisting preferably of Celluloid as in the first instance, and this covering is preferably applied to the core, and will have its ends sealed, preferably precisely like the covering 13 of the scale.

The covering 18 is, however, provided with relatively thick or heavy marginal portions 18a which in practice will preferably be transparent as with ordinary strl ht edges which are formed with wood havmg transparent strips cemented to their ed' But,

of course, the main outstanding advantage of straight edges made in accordance with the present invention, over ordinary wooden straight edges and other straight edges having celluloid strips applied to their edges or marginal portions is that with the present construction the celluloid forms a permanent part which cannot be accidentally detached from the core or body, and which is held in its original straight condition against warping or distortion. which is such an objectionable cliaracteristic of wooden straight edges. These straight edges thus made, can be made very long, their accuracy and permanency being wholly unaffected by their length.

The covering can, like the covering 13 of the scale, be a seamless extruded tube, but it is not essential that it be seamless, for as illustrated in F ig. 10, the tube could be built up from marginal portions 18h, and top and bottom strips 18, with the parts overlapping and cemented together substantially as illustrated, producing a tube having substantially the strength of an extruded seamless tube such as shown in Fig. 9.

Other modifications may be made in some of the details as for example, as shown in Fig. 11, wherein the core or straight edge body here designated 17 has along its marginal edges central outstanding fins or tongues 17b which fit into correspondingly shaped slots in the marginal portions of the sheath or covering here designated 18d.

As above stated, the ends of the covering may be, and preferably are closed and sealed precisely as explained in connection with the scale, and although the sheath, like the sheath of the scale, tightly frictionally engages the surface of the core and is held in conformity therewith, with its ruling edges held in straight, parallel lines, however, I do not wish to imply that there may not be a minute relative movement at times between the core and covering, or portions thereof, especially if the ruler or straight edge is formed of unusual length, or if the coefficient of expansion of the core is much in excess of that of the covering.

lVhile I have described the preferred constructions and the preferred ways of carrying out the invention, as well as the preferred materials, it is to be understood that I am not to be confined to any of the precise materials or details of construction herein illustrated and described, except to the extent that I am limited by the terms of the appended claims, with due regard for equivalency.

Having described my invention, I claim:

1. A ruler comprising a metal stifl'ening core, and a covering, non-metallic of hard, durable, preformed material completely and tightly enveloping the core including its ends and held thereby against substantial movement in any direction.

2. A rulerv comprising a formed non-metallic shell having a ruling edge and a drawn metal core in the shell and serving to impart the features of accuracy, permaneney and stiffness to the shell, the latter completely and tightly enveloping the core and by the latter being held from movement in all directions.

3. A ruler comprising a metal core, and a covering composed of preformed hard eellu loidal material completely and tightly enveloping the core and held by the latter against movement in all directions, said covering being provided with a ruling edge which is maintained straight by the core.

4. A ruler comprising a metal core having one or more flat edges, and a formed celluloidal covering completely and tightly enveloping the core and having one or more edge port-ions of greater thickness than the remainder.

.5. A ruler comprising a metal core having a square edge, and a formed celluloidal shell completely and tightly enveloping the core so as to be held thereon against substantial movement in any direction, said shell having a square ruling` edge adjacent the square edge of the core.

G. A ruler comprising a non-warping core heffing a flat edge, and a formed celluloidal covering completely and tightly enveloping the core including its ends and held from substantial movement thereon in any direction, said covering being provided adjacent the fiat edge of the core with a thickened edge portion provided with a flat ruling edge.

7. A ruler comprising a metal core, a non-metallic shell in the form of a tube enclosing the core and having a ruling edge held straight by the latter, said tube having its ends closed, and non-metallic filler pieces between the ends of the metal core and the ends of the tube.

8. A composite ruler consisting of a hard durable shell forming a ruling edge and a stiff non-warping core which the shell completely envelops whereby the shell is held from movement on the core in any direction, the shell and core comprising preformed elements applied and held tightly together.

9. A composite ruler comprising a stiff, solid, non-warping, non-wooden core, and a shell completely enclosing the core including its ends and composed of hard preformed celluloidal material, the parts being mechanically held together against movement in any direction and in effect forming a solid piece.

10. A composite ruler having top and bottom surfaces extending in parallelism to the outer edges which are transparent, straight and parallel. said ruler being composed of celluloid with a stiffening core therein, the celluloid being relatively thin along the opposite sides of the core and relatively thick along the edges of the core.

11. A composite ruler composed of celluloid and a non-warping core enclosed by the Celluloid, the latter consisting of top and bottom strips and edge strips secured to the irst named strips so as to form a unitary oelluloidal body With ruling edges held straight by the core.

12. A composite ruler composed of celluloid and metal enclosed by the Celluloid, the latter comprising strips extending along opposite sides of the metal and strips extending along the edges of the metal between the first named strips and secured to the latter so as to form a solid unitary enclosure.

13. A ruler comprising a metal stiffening core and a covering of hard, durable nonmetallic preformed material completely and tightly enveloping the core and held thereby against substantial movement in any direction independent of oementing.

In testimony whereof, I hereunto aiX my signature. v

CHARLES H. LITTLE.

CERTIFICATE CF CRRECTCN.

Patent N0. JZSAQ. Gante Sepember i7, i929, to

CHARLES H. UNCLE.

It is heeby eetifed that error appears in the printed speeifieetien of the abm'e numbered patent requiring @affection as fellows: Page 4, Eine 60, eaim 1, strike am the Gemma and compound Wefd non-meay aad ine 62, hefore the wed "permmed" insert he cempeuid wei'd "faonmetallic"; and that the said Lees Paent should be read wifh aese ceireciens therein that the same may ecnm e the record of the ease in the Patent Gice.

Signed and seeed ilis 5th day of Novembei, A. B. i929.

M. J. Moore,

(Seal) Acting Commissioner of Patents.

CERTIFICATE OF CORRECTION.

Patent No. 1,728,439. Granted September 17, 1929, to

CHARLES H. LITTLE.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 4, line 60, claim 1, strike out the comma and compound word non-metallic", and Iine 62, before the Word "performed" insert the compound word "nonmetallie"; and that the said Letters Patent should be read with these corrections therein that the same may eoniorm to the record 0f the case in the Patent Gffice.

Signed and sealed this 5th day of November, A. D. 1929.

M. J. Moore, (Seal) Acting Commissioner of Patents. 

